Ammon News - BEIRUT (Associated Press) - A car bomb rocked a Hizbollah stronghold in southern Beirut July 9, renewing fears of retaliation against the Lebanese Shiite militia for its role in the Syrian civil war.

At least 53 people were injured and several cars were set ablaze when the powerful blast struck the bustling commercial and residential Shiite neighbourhood of Beir El Abed.

There have been growing fears in Lebanon that Hizbollah could face payback for its now overt role fighting alongside Assad regime forces troops inside Syria, including in Homs near the Lebanese border.

The bombing is also likely to inflame already simmering tensions in Lebanon, where deadly clashes between Shiites and Sunnis have grown common as the war in Syria has taken on ever darker sectarian overtones. Some Sunnis in Lebanon, many of whom support Syria's rebels, have expressed growing resentment over what they see as Hizbollah's unchecked power.

Yesterday's bomb exploded in the car park near the Islamic Co-op, a supermarket usually packed with shoppers, and a petrol station.

"The explosion was so strong I thought it was an Israeli air raid," said Mohammad Al Zein, who lives near by. "My wife was sleeping in bed and all the glass fell on her, injuring her in the mouth, arms and legs."

The health minister Ali Hassan Khalil said most of injuries were light, and many of them were caused by breaking glass.

The car park where the bomb went off is a few hundred metres away from Hizbollah's "security square", where many of the party's officials live and have offices. Hizbollah's leader, Hassan Nasrallah, received dignitaries there before the 2006 war. The area was bombed by Israel in that conflict and Mr Nasrallah has gone underground since then, appearing only rarely in public and never for more than few minutes, fearing Israeli assassination.

"This is a message, but we will not bow," said Ziad Waked, a municipal official speaking to Hizbollah's Al Manar television.

With smoke still hanging in the air after the bombing, a group of about 100 outraged Hizbollah supporters stormed through the area, carrying pictures of Mr Nasrallah, shouting in support of their leader and chanting sectarian slogans.

Hizbollah operatives fired in the air to disperse people who attacked the interior minister Marwan Charbel with stones after he inspected the scene of the blast, trapping him for 45 minutes in a building before he was escorted through a backdoor.

"The Shiite blood is boiling," the Hizbollah supporters shouted.

Mr Charbel is seen by some Shiites as sympathetic to the hardline Sunni religious leader Ahmad Al Assir, who was agitating against Hizbollah for months and is now on the run.

The explosion was one of the biggest in the capital's southern suburbs since the end of the 15-year civil war in 1990, and a major breach of a tightly controlled, high-security area.

"It is a large area, heavily populated. No force in the world can protect every area and every street," the Hizbollah parliamentarian Ali Moqdad said.

The president Michel Suleiman said "such acts are a reminder of darker days, which the Lebanese would like to erase from their memories".

Islamist militant groups in Syria have vowed to target Hizbollah areas in Lebanon in retaliation for its role in Syria's conflict. At least one Islamist brigade claimed responsibility for the attack on its Facebook page, but its authenticity could not be verified.

The Syrian National Coalition, the main opposition group, denounced "in the strongest terms the terrorist explosion".

"Targeting civilians is a criminal act that goes against the aims of the revolution and its principles," it said.

Television footage from the scene revived memories of the civil war, when car bombs set by sectarian groups were common. There have been numerous car bombs targeting politicians and journalists since then, but random car bombings have been rare.

Hizbollah operatives in civilian clothes, some of them carrying Kalashnikov rifles, cordoned off the site of the explosion with yellow ribbons. They and Lebanese security officials barred journalists from approaching the site.

Ambulances and fire engines raced to the area, and witnesses said casualties were rushed to two nearby hospitals.

The power of the explosion shattered windows and damaged several buildings. A security official said the bomb was placed in a car and that it weighed 35 kilograms.

In May, two rockets slammed into a Hizbollah stronghold in south Beirut, injuring four people. The rockets struck hours after Mr Nasrallah vowed in a speech to help propel Syria's president Bashar Al Assad to victory in the civil war. Last month, a rocket slammed into the same area, causing no casualties.